Time fuse for projectiles



June 27, 1939.

4 Sheets-Sheet 1 Filed Jan. 29, 1956 R 0 m E a d a W R w a 1 W R w 6 y a E 5 a a M s a 6 Q S U z a 4 a J 1 A Q 1 0 y a ,0 N A E SN 1 J m v w .7. I a II 1IIII|IJ\| r mm IA 1 I ,1, l muw #l 1 I, Q 1 m m. LI Jam /2 1y J n n a F a 0 J J 0V J 6 9 u a M 6 m 4 Z M a 02 7 M 9 Q 6 4 MA ATTORNEY June 27, 1939. A ER 2,164,115

TIME FUSE FOR PBOJECTILES Filed Jan. 29, 1936 4 Sheets-Sheet 3 5o; INVENTOR JEAN LASS ERRE Y %NEY June 27, 1939. J. LASSERRE 2,164,115

TIME FUSE FOR PBOJECTILES Filed Jan. 2 9, 1936 4 Sheets-Sheet 4 JEAN LASSERRE Patented June 27, 1939 UNETE STATES TIME FUSE FOR PROJECTILES Jean Lasserre, Menneval, near Bernay, France, as-

signor to S. A. Recherches Etudes Applications Techniques R. E. A. T., Geneva, Switzerland, a corporation of Switzerland Application January 29, 1936, Serial No. 61,381 In France February 11, 1935 16 Claims.

This invention relates to improvements in time fuses for projectiles.

Mechanical fuses for projectiles have been proposed in which a motor spring, wound spirally around a shaft of the mechanism is tensioned at the firing of the projectile by the inertia of a weight, or is tensioned before the firing during the timing.

Fuses of this kind have the inconvenience that they comprise voluminous and complicated mechanism and include fragile stops for limiting the movements of the timing member such as a key or rotating fuse cap which, in case of 15 breakage, produce the premature bursting of the projectile in the course of manipulation or in the gun or other piece of ordnance.

Motor spring fuses have also been suggested in which the timing member can rotate freely 20 in all directions, that is to say without encountering any stop, but these have a spring which is wound on leaving the factory, which is detrimental to the proper preservation of said fuses.

Fuses with centrifugal action have also been proposed but this type of fuse has the inconvenience of not working at low speeds of rotation of projectiles, fired with a light charge, by field guns.

In all these types of fuses the clockwork movement proper is secured to the body of the fuse and only the wheelwork and gear mechanism for the releasing means of the hammer operate inside the fuse.

The present invention relates to a mechanical time fuse with clockwork movement to which can be added a percussion device of the type in which the regulation of the time of firing is effected by rotating a cap mounted with friction on the fuse body. According to the invention the framework of the clockwork movement (block movement), containing mechanism having a balance regulator escapement, is connected before the discharge, with the frictional rotatable cap of the fuse, in order to effect regulation of the time of firing by the angular displacement of said cap. After the discharge, the said framework rotates on itself inside the fixed cap at a speed regulated by the escapement and under the influence of a motive force generated and transmitted by suitable means, until a determined moment when the said framework produces the release of the percussion means, which are so arranged to be uninfluenced by centrifugal force, in the case of a gyratory projectile. Other frictional and centrifugal means are provided to prevent any deregulation of the fuse at firing.

The accompanying drawings show by way of example various forms of construction of the invention.

Figs. 1 to '7 show in axial section one form of construction of a fuse constructed according to the invention of these figures:

Fig, 1 is a vertical sectional view of the fuse with the parts at rest before the discharge.

Fig. 2 is a similar view showing the fuse timed by a demi-revolution at the discharge of the shot during the acceleration.

Fig. 3 is another view similar to Fig. 1 showing the parts at the timed moment of percussion.

Fig. 4 is an elevation of one of the important members, block movement of the fuse.

Fig. 5 shows in axial section a spring slide intended to transmit the motive force to the clockwork movement.

Figs. 6 and 7 respectively show an axial and cross section of a hooking ring co-operating with the slide shown in Fig. 5.

Fig. 8 shows partly in section and partly in elevation a variation of construction of the driving means of the fuse, and

Fig. 9 is a view similar to Fig. 8 showing another variation of such means.

In the form of construction shown in Figs. 1 to '7 the fuse comprises a body I, a hollow cap 2 angularly displaceable in relation to the body I, the connection between these parts being obtained by a sleeve 4 screwed into the cap 2 and a screw tightening ring 5 threaded around the sleeve 4 and screwed into the body I.

To prevent any axial displacement of the cap 2 the sleeve 4 has at its rear end a shoulderpiece 4* which compresses a friction member 5 arranged between the latter and the rear end of the ring 5. The frictional rotation of the cap 2 in relation to the body I is therefore obtained and regulated by the proper tightening of the sleeve 4 on the cap 2; a screw 2 locks this sleeve 4.

To prevent any untimely loosening of the ring 5 a lock-screw 8 is provided screwed radially into the body I.

The upper end of the cap 2 is terminated by a screw plug 3, locked by a radial screw 3 screwed into the cap.

Airtightness of the fuse between the cap 2 and body I is secured by 2 washers 6 and I of plastic material.

Within cap 2, sleeve 4 and the body I and axially thereof the casing 9 of the clockwork movement (block movement) is mounted rotatable on two ball-bearings one of which (back bearing) is composed of a small sleeve I2 serving as socket to the ball bearing II for the pivot I0, while the other (front bearing) is composed of a roller support I3 mounted at the end of the sleeve 9 of the clockwork movement, which is rotatable between the balls I4 and a track ring I5 keyed axially by a washer of plastic material IT. A washer I6 serves a stop for the balls I4,

multiple teeth and pivoted on a pin 52.

the support l3 and the whole of the block movement 9, as will be explained hereinafter.

The block movement 9 contains the clockwork mechanism provided with regulator and escapement means of any suitable type, and is composed of a pinion 8 which is the prime mover of a wheel train 22, 23, 24, a balance axle 25, a balance 2B and a torsion blade arranged in the axis of the fuse and fixed by one end 21 to the axle of the balance and by the end 28 to the end of the sleeve ll so as to enable the said balance to describe oscillations of great amplitude in order to regulate with exactness the motive force acting on the block movement 9. The pinion |8 gears with the inner teeth I9 of a crown I9 mounted with tight friction in the sleeve 4, the friction being insured by a spring 2| kept under tension by a nut 20 screwed inside the sleeve 4.

The block movement 9 is provided on its lower surface with a circular rim 9 in which is an orifice 9 the function of which will be described hereinafter. This rim 9 co-operates with a percussion device the release of which it operates, the said device comprising a slide 38 carrying a hammer 39 and subjected to' the action of a spring 40. This slide 39 is held tensioned and apart from the priming 50 by a ball 4|, which is kept in the active bolting position by a trigger composed of a plunger 42 having a notch 42. This plunger 42 under the action of a spring 46 is kept in the active bolting position of the ball 4| by a safety device for transport and handling.

This device includes a centrifugal radial bolt 43 having a pin 43 co-operating with a recess 42 provided in the cylindrical stem of the plunger 42 and maintained engaged therein by a spring 44 bearing against a screw plug 45, and a radial pin 41 co-operating with the head 42 of the plunger 42.

The sleeve 9 of the block movement has in its outer surface, for example, two helicoidal grooves 9 preferably of progressive pitch and two grub screws 35 carried by a slide 34 axially displaceable in relation to the sleeve 9, the function of which will be hereinafter described.

Inside the cap is also placed a strong spiral spring 30 of conical form for example, one end of which is fixed to the sleeve 4 and the other end is secured to an abutment device 3|, 32 placed inside a cage 33 freely mounted in the cap 2. At manufacture of the fuse the spring 30 is almost extended and its fore-end is connected to the member 3| of the abutment device.

The fuse includes means intended to prevent any untimely disarrangement of the cap 2 of the fuse by inertia of rotation at the firing of the projectile.

For this purpose there is provided a toothed annulus 53, with inner ratchet teeth, inserted in a circular groove of the body l, which teeth cooperate with one or more spring pawls 5| with One or more inertia operated pins 54 with conical rear ends force the pawl or pawls to engage more quickly with the teeth of the annulus 53 at the firing of the projectile.

Finally the fuse includes an inertia operated locking device for the timing position of the clockwork movement consisting in a circular row of abutments 31 one end of which provided with a bevel edge is intended to engage in the circular rim 9 as the block movement will recoil at firing against these abutments 31 and against the percussion spring 40 which serves as shock absorber spring for the block movement 8.

Working-In the example illustrated in Figs. 1 to 7, the working is as follows:

During manipulation and in the state of rest (Fig. 1),'the fuse is at zero, the two pins of the body and of the cap respectively designated I and 2 are opposite each other and in alignment. In this position the orifice 9 of the circular rim 9 exactly coincides with the axis of the hammer 42. The latter, however, cannot move axially in order to enter the said orifice, owing to the double security provided by the bolt 43 kept in active position by the spring l4 and by the radial pin 41 which obstructs movement of the head of the plunger 42. It should be remembered that in this state of rest the motor spring 30 is relaxed and the balance 26 blocked by a centrifugal bolt not illustrated. In order to proceed with the timing of the fuse the cap 2 is rotated in relation to the body I, either by means of a hand regulator, or by an automatic regulator, using for this purpose the driving pins l and 2. One can likewise make use of the graduations of the fuse which in the example illustrated is numbered from 0 to 40 (Fig. 3) over a serviceable angle of about 350.

In Fig. 2 it is assumed that the timing. has taken place and that the cap has been displaced to the extent of 180 with regard to the body of the fuse, which corresponds to a duration of about 20 seconds. The block movement 9 which is integral with the displacements of the cap before the discharge, as the crown 2| gears with the pinion l8, has also rotated through 180. The safety pin 41 is at that moment diametrically opposite the plunger 42, as well as the orifice 9 which is to liberate the latter. The pin 2 of the cap 2 is likewise diametrically opposite the pin I.

At the discharge of the shot (Fig. 2) the member 33 under the action of its inertia has recoiled, compressing the spring 30, and the abutment ring 3| comes into engagement with the spring hooks 34 on the slide 34 so that from that moment the tension of the spring 30 can act on the block movement 9 through the grub screws 35. However the spring cannot yet relax as the linear acceleration of the projectile continues to act on the member 33 and keeps the latter in the position in which the spring 30 is strained to the utmost.

The inertia of the block movement 9 and of the parts integral therewith also compresses the percussion spring 40 which, as already indicated above, acts simultaneously as a shock absorber for the block movement 9 and the recoil movement of the said block 9 is used to establish its conjunction with the body of the fuse through the intermediary of the abutment pins 31 with bevel-edged cutting ends which penetrate into the more ductile material of the rim 9 provided on the lower surface of the block movement 9.

In this way the block, at the discharge of the slot, is temporarily immobilised and held in the timing position without fear of any alteration of the timing, through rotation inertia.

The spring 40 causes the block movement 9 to be disengaged from the clamping action of the terminals 31 when the longitudinal acceleration has ceased. The block movement 9 thus released can then, under the action of the spring 30 and owing to the intervention of the grub screws 35 and helicoidal grooves 9 rotate around its axis in the direction contrary to the timing and which is preferably that of the direction of rotation of the projectile, so that the rotation inertia of the block movement 9 may assist the rotation of the latter relatively 'to the body l--2 of the fuse (owing to the fact that, contrarily to the outer body l2 of the fuse, the rotation of which is braked by the air during the travel along the trajectory, the rotation inertia of the inner block movement 9, which is not subjected to the braking action, remains substantially constant and therefore tends to produce a rotation of said block movement relatively to the fuse body in the direction of rotation of the projectile, thereby assisting the action of the compression spring 38 in case the latter produces a rotation in the'same direction) As the block movement 9 is simply guided by the two ball bearings i i, M, the friction opposing said rotation is, so to speak, negligible.

The relative movement of the block movement 9 with regard to the movement of rotation of the projectile is obviously very slow, owing to the intervention of the satellite pinion l8 and of the gearing 22, 23, 24 and of the regulator balance 26, since for the example shown this block movement performs a complete rotation on itself within a lapse of about 40 seconds time whereas the speed of rotation of the projectile can attain in the same lapse of time about 24,000 revolutions or more.

While the block movement 9 is performing its rotation, the hammer i2 pushed by the spring 46 abuts on the circular rim 9 and when the orifice arrives opposite the said hammer, the latter rises suddenly into the said orifice under the action of the spring 46, and at that instant the notch 52 coming to the level of the ball 4! retain ing the hammer, instantly releases the latter, which immediately strikes the priming and produces its ignition (Fig. 3). In Fig. 4 the block movement 9 is seen in elevation and illustrated at its actual size. The helicoidal grooves 9 are of progressive pitch, so that the motive power transmitted to the movement may be perceptibly constant the relaxation of the spring 38 proceeds.

Fig. 5 represents in longitudinal axial section the slide 34 provided with hooks 35 and two screw tenons A spring 36 with bent claws 36 hooking to the sleeve t prevents the slide 34, during transport, from quitting the position which it occupies in Fig. l, but, after the cessation of the acceleration at the firing of the projectile, the claws 36* offer only a comparatively slight resistance to the action of the spring 30 which forces them to fold up again as shown in Fig. 3. In Figs. 6 and '7 is shown the abutment device made of rings 3! and 32 fitted one into the other. The ring 32 serves as a guide on the sleeve 9 of the block movement 9 while the ring 3| has radial notches intended to receive the spring hooks 34*, so as to connect the latter with the ring 3 I, both in the axial. and in the angular direction.

A modification of the motor means of the block movement s is shown in Fig. 8. In this construction the motor is a standard clock movement spring 63 the inner end 63* of which is engaged to a hook S5 fixed on the sleeve 9 of the block movement 9 While the other outer end is secured to a hook (it provided on a drum mounted with friction or with a pawl in the cap of the fuse 2, the whole arranged so as to allow, before firing, the winding of the motor spring, by a means accessible from the outside of the fuse.

A modification of the driving means of the fuse is shown in Fig. 9. In this form of construction the motive force for operating the block movement Sis provided for by the centrifugal force generated by the rapid rotation of the projectile during flight.

In this construction there are provided by way of example only three racks fill, El, 62, housed in bores provided in the cap 2 perpendicularly to the axis of the fuse and closed by screw plugs 69 6| and 82 These racks gear with teeth provided on the sleeve fi of the block movement 9 and in order that the motive force transmitted to the movement may be practically constant, the racks can be of diflerent lengths so that at a certain instant the teeth of said racks escape successively from the teeth of the sleeve 8* after each of the racks has actuated the block movement 9 for a certain period.

The mechanical fuse shown in the drawings is of simple action; that is to say the timing is effected during the course of the flight of the projectile.

It can be understood that a known form of percussion device could be added to my improved fuse working by inertia or by recoil at the impact of the; projectile during the trajectory or when it fal s.

Also any known safety means for preventing the untimely percussion of the priming at the commencement of the flight of the projectile could also be combined or associated with my improved fuse.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A mechanical time fuse for artillery p-rojectiles having a hollow body, a mechanism for regulating the operation of the time fuse comprising a motor mounted in said body and connected thereto, a rotor connected to said motor to be rotated thereby, a clock mechanism entirely lodged in said rotor and connected to said fuse botdy for controlling the speed of rotation of said ro or.

2. A mechanical time fuse for artillery projec tiles having a hollow body, a mechanism for regulating the operation of the time fuse comprising a compression spring motor mounted in said body and connected thereto, a rotor connected to said motor to be rotated thereby, a clock mechanism entirely lodged in said rotor and connected to said fuse body for controlling the speed of rotation of said rotor.

3. A mechanical time fuse for artillery projectiles having a hollow body, a mechanism for regulating the operation of the time fu e comprising a compression spring motor mounted in said body and connected thereto, a rotor connected to said motor to be rotated thereby, a clock mechanism entirely lodged in said rotor and transmission means forming a part of said clock mechanism and eccentrically carried by said rotor, said transmission means connecting said rotor to said fuse body and operable by rotational movement of said'rotor relative to said fuse body to actuate said clock mechanism for controlling the speed of rotation of said rotor.

4. In a fuse according to claim 3, said hollow body is constituted by a fixed base and by an adjustable timing cap, a fir t sleeve with a shoulder piece fixed to said cap, a second sleeve concentric with the first fixed to said base, adjustable friction means between the two sleeves, permitting a rotation of one with respect to the other, a toothed ring meshing constantly with said transmission means carried by said rotor, means for maintaining said ring in mesh with said first sleeve b-y adjustable friction,

5. In a time fuse for an artillery projectile, a spring motor therefor comprising a main spring of the compression type, a main shaft, inertia means arranged to compress said main spring in which due to acceleration of the projectile upon firing of the same, and to maintain said main spring in its compressed state during said acceleration, and means to couple said main spring to said main shaft upon cessation of acceleration whereby said main spring will cause said main shaft to rotate and operate said time fuse.

6. In a mechanical time fuse for an artillery projectile including a cap member, a spring motor therefor comprising a main shaft rotatably mounted in the axis of said fuse, a main spring of the compression type co-axial with said main shaft, means to non-rotatably fix the lower end of said main spring to said cap member, inertia means arranged to compress said main spring due to acceleration of the projectile upon firing of the same, at least one helical groove in said main shaft, a sleeve slidably mounted upon the main shaft and provided with at least one spur engaged in said groove and means to couple the upper end of said main spring to said sleeve at the cessation of acceleration of said projectile, whereby the expansive action of the main spring will turn said main shaft and operate said fuse.

7. Fuse according to claim 6, in which said inertia means adapted to compress said main spring comprise a small mass slidably mounted on said main shaft and covering the upper end of said main shaft.

8. Fuse according to claim 6, in which said means adapted to couple the upper end of said main spring to said sleeve comprises a ring slidably mounted on said main shaft and integral with the upper end of said main spring, a number of radial teeth carried by the inner periphery of said ring, a number of elastic hooks carried by said'sleeve and adapted to engage said teeth.

9. Fuse according to claim 6, in which said sleeve comprises elastic hooking means for maintaining the sleeve at the lower part of said main shaft until the end of the acceleration of the projectile.

10. Fuse according to claim 6, in which said helical groove has a progressive pitch.

11. In a mechanical time fuse, a hollow body H formed of a fixed base and an adjustable setting cap, a rotor rotatably and slidably mounted in said body, a firing-pin plunger axially slidable in said base, a compression spring interposed between said rotor and said plunger tending to actuate said plunger, locking means normally holding said plunger in an inoperative position, a notched circular rim formed on the bottom of said rotor, a mechanism cooperating with said rim to normally lock said locking means in plunger holding position after the setting of the fuse and to release said locking means at the expiration of a predetermined time and an auxiliary mechanism cooperating with said first named mechanism to prevent release of said locking means before the setting of the fuse, independently of said rim.

12. In a mechanical time fuse, a hollow body formed of a fixed base and an adjustable setting cap, a rotor rotatably and slidably mounted in said body, a firing-pin plunger axially slidable in said base, a compression spring interposed between said rotor and said plunger tending to actuate said plunger, a locking ball normally holding said plunger in an inoperative position, a notched circular rim formed on the bottom of said rotor, a mechanism cooperating with said rim to normally look said ball in plunger holding position after the setting of the fuse and to release said ball at the expiration of a predetermined time and an auxiliary mechanism cooperating with said first named mechanism to prevent release of said ball before the setting of the fuse, independently of said rim.

13. In a mechanical time fuse for an artillery projectile having a setting cap with a cylindrical bore and a base having therein an axial bore; a clockwork casing with a notch therein rotatably and slidably mounted in the cylindrical bore of said setting cap, a circular series of bearing balls for rotatably mounting said casing, a lower cylindrical race for said balls slidably mounted in the axial bore of the base of the fuse, a cylindrical firing pin plunger slidably mounted in said axial bore under said race, a shock absorbing percussion .coil spring interposed between said race and said plunger, means to hold normally said firing pin plunger in a cocked position with said spring in a compressed state, and a shiftable release shaft associated with and under the control of said notched clock work casing, and spring means to shift said release shaft to release said holding means when the notch in said clock Work casing coincides with said release shaft during the flight of the projectile.

14. In a mechanical time fuse for an artillery projectile, said fuse having a base and a setting cap each provided with a longitudinal bore, and said base having a radial bore; a firing pin slidably and axially mounted in the base of said fuse, a spring acting on said firing pin, a locking ball slidably mounted in the radial bore of said base and normally restraining said firing pin against the action of said spring, a release shaft slidably mounted in the longitudinal bore of said base and normally holding said ball immovable, a spring acting on said release shaft and tending to force it to a position to release said ball, a cylindrical clockwork casing rotatably and slidably mounted in the bore of said setting cap, a timing rim formed in the bottom of said casing, a release notch provided in said timing rim, safety means normally holding said release shaft in a position whereby it holds said ball immovable, releasable means to couple positively said casing to said setting cap before the firing of the projectile and means actuated by the setback of this casing due to firing of the projectile, to hold it momentarily coupled to said base during the acceleration of the projectile, said casing, following said momentary coupling, being actuated to position said release notch in line with said release shaft, whereby said release shaft is moved to release said locking ball and said firing pin.

15. Fuse according to claim 14, in which said means for momentarily coupling said casing to said base are constituted by a number of circumferentially arranged sharp studs integral with said base and engaging into the bottom of said casing when the latter moves back.

16. In a fuse according to claim 1, in which said hollow body is constituted by a fixed base and by an adjustable timing cap; a number of circumferentially arranged pawls integral with said cap, an inner tcothing integral with said base, inertia means integral with said cap for bringing said pawls into engagement with said tcothing for preventing any angular misadjustment of said cap with respect to said base after the firing of the projectile.

JEAN LASSERRE. 

